i disagree with 5, making bigger cut will simply make more and eventually most people to find trading elsewhere, on forums, websites - and since such large portion of people will start doing it, someone will also make it convenient for unsophisticated users as well.
I liked some of the idea. I think there would be more ramification than those he suggested..but I also disagreed with five. If the items are too expensive to post, then people will develop a third party way to handle transactions of this nature. Since blizzard has out right said that they balance the loot tables around the AH, things would have to be changed at a fundamental level before this would even be applicable, assuming it even would after whatever changes are made have gone through.
The only real complaint I have with the game is that loot for my level does not drop nearly as often as I think it should and when it does, it's hardly ever a stat I can use or is for a class other than my own. I suppose if I was playing in a group on a consistent basis instead of by myself, this could be mitigated since theoretically other classes could be in on it and they might get what I need...but I wouldn't be surprised if the loot tables adjust some how to prevent that from happening.
My suggestion regarding the listing charges and auction house cut is meant only for the gold auction house - not the RMAH. And is only a part of the changes.
What this addresses is the low minimum buyout prices in the auction house - which are the real problem. It won't affect the super high pricing. Here's some modeling to explain:
Say a level 40 item sells to a vendor for 300 gold, and you want to sell it on the auction house. You would need to pay 300 gold to list it. The default minimum bid would be 300 gold.
However, if the auction house cut was 50%, then you'd only get 150 gold for it if it sold for the minimum. In order to break even, you'd need to set the minimum bid to 600. But then, you'd only get as much money as you spent to list the item in the first place. Given the opportunity cost lost by not selling or salvaging the item, you'd need to sell it for at least 1200 in order to make 300 gold more than the amount you would have made vendoring it.
Now, listing it for only 1200 gold will work if you're SURE it will sell. If it doesn't, you're out 300 gold. So you'll want to pad the price of your items so that you can cover the costs associated with auctions that get no bids - standard mark-up like this is 5 times cost. So you'll want to look at a minimum bid of around 6000 gold (with some discounting to move certain merchandise quickly).
Obviously if its a premium item, you'll want a higher minimum bid, or if its an item you're pretty sure will move quickly - you'll want to put a fair buy out on it.
This puts an average low end price on a level 40 item to 6000 gold. This isn't an exorbitant amount of money, but at level 40 you'd need to clear an entire act to pull the 100,000 to buy a whole set of gear. By then, you'd have leveled some, and gotten some drops, maybe blacksmithed a few things - and instead you might pick up the one or two pieces you've got that have lagged behind a few levels on the AH at a higher quality for say 50,000 a piece. You will also see a higher average quality - and less items to sift through because crap items just won't be worth popping up on the auction house because of the negative financial impact if they don't sell.
Right now, you can pick up a set of passable level 40 gear for around 16k gold. That's way too low, and since there's no risk for the player to put up prices that low, there's no reason for people to increase prices to the point at which it becomes an actual choice as opposed to a "no brainer" to the consumer as to which is the better option.
Blacksmith combines cost around 1500 - 10000 for items between level 35 and 41 (10,000 is a shield and a bit of an anomaly - most items are less than 5,000). So this would be more competitive with the AH as an equipment source - ESPECIALLY if you can force a mainstat mod on the items. And it is a bit more satisfying (in my opinion) to make something you'll use as opposed to picking it out of a window (back to the economy of fun here).
Hopefully that will explain my suggestion in a bit more detail from an economics perspective. It's really a minor change - it just forces some behaviors with regards to the selling side of the auction house to require a bit more skill on the part of the seller, and would generally raise prices across the board to be more inline with other equipment acquisition methods. Obviously with the low-end required prices - we aren't really affecting equipment in the 1m gold range - just in the lower end "gear yourself up for content" range.